Need help: Hum sound/noise, blast sound

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koleloi

Member (SA)
Apr 17, 2014
242
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Hochiminh city, Viet Nam
I just pick my m70 few days ago and it had some issues that annoys me alot. Please guys give me some advice and suggestion to deal with these:

- It make a blast sound when I turn on the box + those VU suddenly jump hard over middle point. When turn off the box, it explodes a short sound on the left speaker, I can see the woofer move a mile.
- It constantly produces a hum/drone sound from each speaker that can heard clearly from few meters. It's hard to be heard if turn volume over 3 but it's ever-present. Move up to volume to ten just make it a bit louder. I noticed that the noise in left speaker is minimum if volume is at around 5.

The output sound level of the box is normal. Volume controls work fine but both bass and treble control doesn't work.

I already did spray all the sliders and function switch with contact cleaner but no help.

Those problems are annoying me so much. So any help would be greatly appreciated guys. Thank you so much!
 

Ca880

New Member
Oct 2, 2015
15
0
1
The DC power supply fiter cap is C520. It is a 2200uF cap on the main board. You will not see it unless you remove the main board from the radio chassis. I removed mine and replaced it with a 4700uF / 35wvdc cap. $1.87 from Digikey. Digikey P/N

493-12483-ND
If you are looking for an alternate cap, keep in mind the lead spacing is 7.5mm/.295" and the diameter is 16mm/ .630"
 
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